1. Field of the Invention
This invention relates to paperboard containers and more particularly to liquid-tight paperboard containers, examples of which are disposable containers adapted for distribution of beverages, milk and other dairy products, which eliminate edge wicking through exposed panel edges in the interior of the container.
2. Description of the Prior Art
Paperboard containers are widely used in the dairy and other industries to package milk and other liquids and substances. Because these containers are formed from blanks cut from large paperboard sheets, there are raw or open edges along the cut lines which are subject to wicking or penetration by the product within the container. In the past this edge wicking problem was avoided by folding under the open edges or cut lines along the full length of the side seam and the bottom tuck panel of the container so as to provide no exposed panel edges in the side or bottom interior of the container, thereby rendering the carton impervious to liquids stored therein. Such a method for folding under the entire edge of one bottom panel is disclosed in U.S. Pat. No. 3,294,310 to Miller, issued Dec. 27, 1966. The sealing the interior of the carton due to the build up of paperboard thicknesses along portions of the interior seal, which creates an inherent channel area that is difficult to seal effectively. In addition, the Miller method necessitates use of a carton blank having an oversize bottom panel.
An improved method is disclosed in U.S. Pat. No. 3,412,922 to Miller, issued Nov. 26, 1968, in which two parallel slits are made in the end of one bottom panel and the tab or portion of the panel between the slits is folded back. Only the folded-back tab thereby formed is inserted into the interior of the bottom closure so as to present no open edge in the interior of the container.
Thus, with the method described in the Miller U.S. Pat. No. 3,412,922 it is necessary to fold under the entire open edge of the bottom tuck panel. The method described in the Miller U.S. Pat. No. 3,412,922 requires slits to made in the bottom tuck panel before and the portion of the panel between the slits to be folded under during forming and sealing the bottom.
The present invention provides a new carton blank configuration which permits the formation of a nonwicking bottom for liquid containers without folding or slitting the bottom tuck panel before beginning the bottom forming and sealing process.